Open-end spinning process and device for its implementation

ABSTRACT

An open-end spinning process in which the fiber sliver is separated into single fibers and in which the separated fiber material is brought by an air stream to a collecting surface from which it is drawn off while being twisted. According to the instant invention the fiber material is deposited on a collecting surface moving in the direction of thread draw-off, is then twisted and is continuously drawn off said collecting surface in form of a thread. The single fibers are fed upon the collecting surface in the direction of said collecting surface&#39;s movement, whereby an alignment of the fibers on the collecting surface takes place. The doubling process is separated from the spinning process as the fiber material is bundled and/or doubled on the collecting surface into a fiber sliver with the fiber mass required for the desired thread. The twisting process takes place independently of the collecting surface by means of a known twisting mechanism.

The instant invention concerns an open-end spinning process in which amass of fibers in the form of a band is separated into separate fibersand in which the separated fiber material is fed to a collecting surfacein an air stream, then to be drawn off from said collecting surfacewhile being twisted, and further concerns a device for theimplementation of said process.

Among the different open-end spinning processes the open-end rotorspinning process and the open-end friction spinning process have gainedconsiderable importance. The latter has the special advantage over therotor spinning process of requiring lower RPMs of the spinning elementsthan in the rotor spinning process, while higher production speeds arenevertheless attainable. The thinner yarns can be spun more efficiently.However, the quality of the yarns produced by the friction spinningprocess is unsatisfactory because the individual fibers are not fed intothe spinning nip in a parallel position to the yarn axis as would berequired for their orderly incorporation into the freely rotating yarnend. Measures have been proposed in the past in order to bring thefibers into a position which is nearly to the yarn axis as they are fedinto the nip, for example mechanically, by means of a centrifugal disk(DE-PS No. 2,720,625) or pneumatically, by means of a cascade-likeincrements of the air pressure in the path of the fibers (DE-OS No.2,732,678) or by feeding the fibers at an oblique angle in relation tothe direction of thread draw-off, combined with an air streamessentially parallel to the thread axis (DE-OS No. 2,943,063). Yarnquality is not satisfactory however, in spite of these measures,especially at high spinning speeds.

It is the object of the instant invention to create an open-end spinningprocess making it possible to produce a yarn of good quality at highproduction speeds, and to create the device for the implementation ofthis process.

This objective is attained by the instant invention with a process wherethe fiber material, in the form of individual fibers, is deposited on acollecting surface moving in the thread draw-off direction and is drawnoff continuously from said collecting surface in the form of a threadwhile being twisted. No fibers are added on to the already finishedthread but are always fed to the thread end.

Oriented depositing of the fibers on the collecting surface is obtainedby feeding the separate fibers in direction of the collecting surface'smovement. The doubling process is separated from the spinning process bybundling and/or doubling the fiber material on the collecting surfaceinto a fiber bundle containing the fiber mass required for the desiredthread. The twisting operation is carried out suitably by a knowntwisting mechanism, independently from the collecting surface.Provisions can be made here for the fiber sliver being formed on thecollecting surface to be deposited into the spinning nip formed by twocylinders in close proximity to each other and driven in the samedirection, to be twisted into a thread and to be drawn off in continuousoperation.

The device to carry out the process is characterized by a collectingsurface moving in the direction of the thread draw-off and followed, inthe direction of thread draw-off, by a twisting device and by a draw-offdevice.

In a preferred embodiment the collecting surface is placed on theperiphery of a disk-like cylinder. The surface speed of the collectingsurface is approximately equal to that at which the thread is drawn off,so that the full mass of fibers required to form the finished thread iscollected on the collecting surface and is conveyed in form of a fiberbundle in the direction of the twisting device where it is twistedtogether into a thread.

Doubling does not take place in the rotating zone but in a rotation-freezone. This separation of rotation and doubling produces a yarn of goodquality.

A delay and the ensuing further parallel positioning of the fibers aswell as doubling of the fibers on the collecting surface, (said doublingbeing increased as a function of said delay), is obtained if the surfacespeed of the collecting surface is kept lower than the thread draw-offspeed.

In order to deposit the conveyed fibers in a precisely defined width onthe collecting surface, said collecting surface is made in form of agroove. The width of the groove corresponds approximately to thethickness of the arriving fiber material so that a fiber bundle isformed which closely corresponds to the yarn diameter. The preferredconfiguration of the cross-section of the groove is V-shaped. A roundedgroove bottom favors the propagation of torsion within the fiber bundle.Secure conveying of the fibers throughout the collecting surface isensured by holding the fibers on said collecting surface by pneumaticmeans.

In a preferred embodiment the collecting surface is subdivided intosectors. In this case the collecting surface has a first sector with aninwardly directed air stream extending in the sense of the collectingsurface's movement from the fiber feeding point up to a second sector.Preferably the collecting surface is subjected to an outwardly flowingair stream in the area of the second sector. For this purpose the secondsector is connected to the atmosphere.

In order to maintain a defined flow of air within the collecting surfacearea, said collecting surface is enclosed in a housing.

An opening device is provided before the collecting surface to separateand feed the fiber material onto the collecting surface. The openingdevice is connected to the collecting surface by a fiber channel whichopens upon the collecting surface essentially at a tangent in the senseof the collecting surface's movement, said fiber channel having anoutlet which is adapted to the width of the collecting surface.

Even greater precision in feeding the fibers onto the collecting surfacein the direction of its movement is achieved if no fiber channel isused. This is possible if the housing of the opening device and thehousing of the cylinder are immediately next to each other and connectedby a connecting opening. Preferably the collecting surface is equippedwith a cleaning device. A pair of friction rollers, driven in the samedirection and forming a spinning nip, can serve as the twisting devicewhereby the axis of rotation of the collecting surface cylinder is in aplane perpendicular to the spinning nip. In another embodiment apneumatic twisting device is installed after the collecting surface inthe sense of thread draw-off.

Two examples of embodiments according to invention are shown hereinbelowthrough the following drawings:

FIG. 1 shows a cross-section of an embodiment of the spinning deviceaccording to the invention having a pair of friction rollers whichassume the role of twisting device.

FIG. 2 is a side-view or the cross-section of the invention seen in FIG.1.

FIG. 3 shows a cross-section of another embodiment of the deviceaccording to invention with a pneumatic twisting device.

FIG. 1 shows one of two friction rollers 1 and 2 which, as can be seenin FIG. 2, are installed parallel and in close proximity to each other.Friction rollers 1 and 2 are driven in the same direction in a mannernot shown in further detail, such as for example by means of atangential belt. The friction roller 2, rotates away from the spinningnip and is not perforated and not subjected to suction. Friction roller1, rotating towards the spinning nip has a perforated casing surface andis equipped with a suction insert 10 (FIG. 2) connected to a suctiondevice (not shown). Suction insert 10 is provided with a slit 11extending in the longitudinal direction of spinning nip 3, and thesuction air stream is drawn through said slit. The design of thefriction rollers has no bearing upon the invention. It would also bepossible to subject both friction rollers to suction air.

The separation of the fiber material to be spun into single fibers iseffected by means of an opening device installed in a housing 4. Saidopening device consists of an opening roller 5 with a garniture,preceded by a feeding device which consists of feeding roller 6,functioning jointly with a feeding trough 60.

Between the opening roller 5 and the friction rollers 1 and 2, adisk-like cylinder 7, enclosed in housing 4 is rotatably supported onbearings. On the periphery of said cylinder is a collecting surface 70.Collecting surface 70 is connected to opening device 5 through a fiberchannel 51 which opens nearly tangentially onto collecting surface 70 inthe direction of its rotation, the width of said fiber channel beingadapted to the width of collecting surface 70.

Cylinder 7 is supported by roller bearings 81 on a hollow shaft 8mounted in the machine frame and is suitably driven by a tooth belt inthe direction of arrow P. Cylinder 7 should reach as far as possibleinto the nip zone.

The collecting surface 70 is preferably grooved, the bottom of thegroove being rounded so that the fiber material required for theformation of the yarn may be accepted completely and may be preformed inwidth and thickness. As it is conveyed in direction of the spinning nip3, the fiber material is held fast by a suction air stream on the bottomof groove 72 which forms the collecting surface 70 and is perforated.

For this purpose, the disk-like cylinder 7 is connected to a suctiondevice (not shown) through a hollow shaft 8. The suction air streamhowever takes effect only in a sector I on the collecting surface, saidsuction air stream extending in the sense of movement of collectingsurface 70 from the point of arrival 30 of the fibers on said collectingsurface 70 up to a second sector II. The second sector II is kept freefrom the suction air stream by means of the separator walls 74. It may,however, be useful to introduce an air stream into sector II, said airstream flowing outwardly through collecting surface 70 in the directionof the spinning nip 3. Since the friction roller 1 is subjected tosuction and since housing 4 is sealed and extends beyond the frictionrollers 1 and 2, this air flow is created by sucking in air from SectorII. The air required for this is brought in through a pipe 82, insertedin the hollow shaft 8, said pipe 82 connecting Sector II with theatmosphere.

In order to avoid random air currents in the area of fiber feeding tothe collecting surface 70 and a in order to expose the fibers conveyedthrough fiber channel 51 exclusively to an air stream ensuring theiroriented depositing on collecting surface 70 in the direction of itsmovement, a Sector III, following Sector II and reaching up to theoutlet of fiber channel 51 is kept free from air streams by means of afixedly mounted screen 75. In addition to this, seals 41 and 42 areinstalled on housing 4, at the beginning and at the end of this SectorIII. At the same time, seals 41 and 42 also act as stripping devices andexert a cleaning or wiping action upon collecting surface 70.

The opening device consists, as is known to the art, of a rapidlyrotating garniture roller fitted with saw tooth wire said roller beingtightly enclosed in a housing in the walls of which dirt separatoropenings are provided.

For the spinning process, the fiber material is brought by wa of afeeding trough 60 in form of fiber sliver B by means of feeding roller 6to the opening roller 5 which separates the fibers. The negative airpressure in Sector I of cylinder 7 produces a conveying air stream whichconveys the separated fibers through fiber channel 51 to collectingsurface 70 on which the fibers are deposited.

The individual fibers coming from the opening device 5 join thepreviously supplied fibers one by one and are incorporated into thethread end. The surface speed of collecting surface 70 is approximatelyequal to the thread draw-off speed. Thus, an accumulation, and therebydoubling of the fiber mass required for the finished thread takes placeon collecting surface 70. Friction rollers 1 and 2 now only serve as atwisting device, so that no overfeeding to the already finished threadtakes place.

If the surface speed of the fiber collecting surface 70 is slightlylower than the thread draw-off speed, the doubling process on collectingsurface 70 is further increased. At the same time a pull is exerted uponthe forming thread on the collecting surface, so that a stretching ordrafting effect occurs. The movement of collecting surface 70 in thedirection of thread draw-off decreases the requirement of force neededfor thread draw-off, so that the thread is not overloaded and so that nounwanted delays occur.

The embodiment shown in FIG. 3 is different from the device shown inFIGS. 1 and 2 essentially, in that a pneumatic twisting device is usedto impart rotation, and in that the housings defined by walls 40 and 40'of the opening roller 5 and of cylinder 7' are installed in immediateproximity of each other so that fiber channel 51 is eliminated. The twohousings are connected through a common connection opening 43 throughwhich the fibers are conveyed from the opening roller 5 to thecollecting surface 70. Cylinder 7' is adapted here to the width ofopening roller 5 and is equipped with guides tapering into a V whichlead the fibers together from th width of the opening roller 5 to thewidth of collecting surface 70. Because of the direct transition of thefibers from opening roller 5 to collecting surface 70, interferinginfluences throughout a fiber channel are avoided. Also, less conveyingair is required because of the shorter conveying distances. Cylinder 7'is subjected to suction air, essentially in order to hold the fibers oncollecting surface 70.

The opening roller 5 is equipped with a guiding plate 53 which isattached to housing 4 and which extends from the point on which thefibers detach themselves from the opening roller nearly to thecollecting surface 70. Guide plate 53 performs a sealing function at thesame time. It ensures the connection with the fixed screen 75 in SectorIII and, if need be, also with an additional sealing means 42 attachedto guide plate 53 to prevent the fibers from being exposed to an airstream flowing in a direction opposite to the movement of collectingsurface 70, so that they may exclusively follow the air stream in thedirection of the rotation of collecting surface 70 to be deposited onsaid collecting surface 70 in an oriented fashion. The seal 41,installed at the beginning of Sector III in the sense of rotation ofcylinder 7, is preferably used in this embodiment too, and similarly tothe seal 42 attached on guide plate 53 it also serves as a cleaningdevice. Between connecting opening 43 and Sector II a screen 54 isfurthermore installed, said screen extending close to collecting surface70 (FIG. 3). Screen 54 prevents the fibers from being seized by thesuction air flowing towards friction roller 1 before they are depositedon collecting surface 70. Furthermore, the fibers are protected from theair stream coming from friction rollers 1 and 2 under whose influencethey could leave the collecting surface 70 too early and out of control.In order to ensure better fiber guidance from the opening device 5 up tocollecting surface 70, a fiber guide plate 55 can additionally beprovided following the connecting opening 43.

The pneumatic twisting device used to impart rotation contains aninjection nozzle 90 and following it a twisting nozzle 91. The twistingdevice is fixedly installed in a housing part that is pivotable aroundan axis 92, in the sense of thread draw-off, said housing part beingprovided with air inlet openings 93 and 94 for the injection nozzle 90and for the twisting nozzle 91. A bypass 95 in housing 4 is connected tothe outlet of the injection nozzle 90 and is located in immediateproximity to the collecting surface 70. As shown for the example of inFIGS. 1 and 2, the twisted thread is drawn off from the collectingsurface 70 by means of a pair of draw-off rollers 9. It is, of course,possible to use other pneumatic or mechanical twisting devices to impartrotation. In all other respects the functions of this device areidentical to those of the device in FIGS. 1 and 2.

I claim:
 1. An open-end spinning process for converting a fiber sliverinto yarn, comprising the steps of:(a) separating said fiber sliver intoindividual fibers; (b) aligning said fibers along their longitudinalaxes; (c) conveying said aligned fibers in an air stream to a collectionsurface; (d) moving said collection surface in the direction said fibersare conveyed by said air stream; (e) depositing said fibers onto saidcollection surface in a continuous bundle of aligned fibers, said fibersbeing aligned in the direction of said surface is moving; (f) removingsaid continuous bundle of fibers from said collection surface in adirection tangent to said collection; (g) twisting said bundle of fibersinto yarn as it is removed from said collection surface; and (h) windingsaid yarn onto a package.
 2. An open-end spinning process as set forthin claim 1, wherein said fiber bundle contains the fiber mass needed toform the desired yarn.
 3. An open-end spinning process as set forth inclaim 1, wherein said yarn bundle is twisted after it leaves thecollection surface.
 4. An open-end spinning process as set forth inclaim 3, wherein the fiber bundle formed on the collection surface isdeposited in the spinning nip formed by two cylinders in close proximityof each other and driven in the same direction for twisting said bundleof fibers into a yarn.
 5. An open-end spinning apparatus for convertinga fiber sliver into yarn, comprising:(a) means for separating fibersfrom said fiber sliver and for aligning said fibers along theirlongitudinal axes; (b) pneumatic means for conveying said aligned fibersin the direction of their longitudinal axes; (c) collection means forcollecting said aligned fibers onto a surface moving in the directionsaid fibers are conveyed by said pneumatic means in the form of acontinuous bundle of fibers; (d) means for removing said continuousfiber bundle from said moving surface; (e) means for twisting saidbundle of fibers into yarn as it is removed from said moving surface;and (f) means for winding said yarn onto a package.
 6. An open-endspinning apparatus as set forth in claim 6, wherein said collectionsurface is located on the periphery of a disk-like cylinder.
 7. Anopen-end spinning apparatus as set forth in claim 5, wherein the surfacespeed of the collection surface is approximately equal to the speed ofyarn draw-off.
 8. An open-end spinning apparatus as set forth in claim5, wherein the surface speed of the collection surface is less than thespeed of yarn draw-off.
 9. An open-end spinning apparatus as set forthin claim 5, wherein the collection surface has a groove formed therein.10. An open-end spinning apparatus as set forth in claim 9, wherein thewidth of said groove corresponds approximately to the thckness of thefiber bundle.
 11. An open-end spinning apparatus as set forth in claim9, wherein the cross-sectional shape of said groove is V-shaped.
 12. Anopen-end spinning apparatus as set forth in claim 9, wherein the bottomof said groove is rounded.
 13. An open-end spinning apparatus as setforth in claim 5, wherein said collection surface is perforated and airis drawn through said perforations.
 14. An open-end spinning apparatusas set forth in claim 13, wherein said collection surface has a firstsector with an inwardly directed air stream passing inwardly throughsaid collection surface and said fibers to hold said fibers onto saidsurface for a predetermined arcuate sector of said collection surface.15. An open-end spinning apparatus as set forth in claim 14, wherein anoutwardly directed air stream flows through said collection surface inthe area of a second sector for removing said fiber bundle from saidsurface.
 16. An open-end spinning apparatus as set forth in claim 15,wherein said second sector of the collection surface is connected to theatmosphere.
 17. An open-end spinning apparatus as set forth in claim 15,wherein said collection surface is enclosed in a housing.
 18. Anopen-end spinning apparatus as set forth in claim 17, wherein thecollection surface is preceded by said means for separating said fiberswithin said housing.
 19. An open-end spinning apparatus as set forth inclaim 18, wherein said means for separating fibers from said fibersliver is connected to said collection surface by a connecting channelextending tangentially from said separating means to said collectionsurface, whereby the outlet for said connecting channel is adapted tothe width of said collection surface.
 20. An open-end spinning apparatusas set forth in claim 18, wherein the housing for the fiber separatingmeans and the housing for said collection means are located in theimmediate proximity to each other and are connected to each otherthrough a connecting opening.
 21. An open-end spinning apparatus as setforth in claim 20, wherein fiber guiding elements are disposed in thearea of said connecting opening.
 22. An open-end spinning apparatus asset forth in claim 21, wherein a screen is disposed adjacent to saidcollection surface at the end of said first sector.
 23. An open-endspinning apparatus as set forth in claim 5, wherein means are providedfor removing residual fibers from said collection surface after saidyarn bundle is withdrawn therefrom.
 24. An open-end spinning apparatusas set forth in claim 5, wherein said twisting means comprises a pair offriction rollers driven in the same direction and forming a spinningnip, whereby the axes of movement of said collection surface lies in aplane perpendicular to said spinning nip.
 25. An open-end spinningapparatus as set forth in claim 5, wherein said twisting means comprisesa pneumatic twisting element.